The invention relates to an electromagnetically operated valve construction wherein permanent-magnet action is effective to latch, i.e., to retain, a selected open or closed condition of the valve.
U.S. Pat. No. 3,814,376 describes a magnetically operated two-position latching valve having an armature that also serves as a movable valve element, with valve action, and inlet and outlet flow connections, all at one axial end of the construction. The armature is movable to its two positions by and is latched in one or the other of its two positions solely by magnetic flux. An elongate armature is actuated from one to the other of its positions by excitation of two solenoid coils in a first polarity relationship, and return from said other to said one position is effected by excitation of the two solenoid coils in a second or reversed polarity relationship. The armature is a relatively massive cylinder which is guided in an elongate bore; it is therefore subject to friction which can become a source of unreliable operation, in the event of grit or other particles which may be borne by fluid controlled by valve action. The mass of the armature also makes the construction vulnerable to an inertial response to mechanical shock, wherein an unwanted open-valve condition is an inadvertent occurrence, or wherein an open-valve condition is inadvertently shut down.